Objectives: To estimate the occurrence of and associations between upper respiratory tract infections in preschool children, and to assess constitutional and environmental factors as determinants of these infections.
Design: Population-based cross-sectional study.
Setting: Oslo, Norway.
Participants: Preschool children, aged 4 to 5 years (3853 completed questionnaires).
Main outcome measures: Acute and recurrent acute otitis media, tonsillopharyngitis, common cold, and rhinitis.
Results: Upper respiratory tract infections were common at age 4 years. During the last month, 7.1% of the children had acute otitis media and 7.5% experienced tonsillopharyngitis. Corresponding figures for common cold and rhinitis were 58.3% and 16. 4%, respectively. During the last 12 months, 9.5% of the children experienced more than 1 bout of acute otitis media, 6.9% had more than 1 tonsillopharyngitis episode, 47.7% contracted more than 2 common colds, and 3.2% had rhinitis weekly or monthly. The lifetime prevalence of recurrent acute otitis media (>/=4 episodes in any 12-month period) was 12.7% (n = 473). Bivariate correlations showed small-to-moderate relationships between the infections. Common cold was only weakly related to otitis media, tonsillopharyngitis, and chronic rhinitis. The probability for developing acute otitis media was almost 4-fold increased in children who had tonsillopharyngitis in the last year (adjusted odds ratio = 4.19; 95% confidence interval, 3.09-5.66). In logistic regression analysis, atopic disease was a strong determinant of all upper respiratory tract infections. Low birth weight increased the risk of acute otitis media. Day care attendance and the presence of siblings, which were considered to be indicators of exposure to respiratory pathogens, increased the risk of upper respiratory tract infections.
Conclusions: In preschool children, acute otitis media, tonsillopharyngitis, and common cold were quite common, while chronic rhinitis was less prevalent and strongly associated with atopic disease. Attendance at day care centers increased the risk of upper respiratory tract infections in this age group, although the effect was weaker than that in younger children.